When comparing OCaml vs ClojureScript, the Slant community recommends ClojureScript for most people. In the question“What are the best Functional languages to learn for web-frontend development?”ClojureScript is ranked 2nd while OCaml is ranked 6th. The most important reason people chose ClojureScript is:

Figwheel builds your ClojureScript code and hot loads it into the browser as you are coding! Every time you save your ClojureScript source file, the changes are sent to the browser so that you can see the effects of modifying your code in real time.

Pros

Pro

Encourages functional style

It steers you towards a functional style, but doesn't bother you with purity and "monads everywhere" like other languages, such as Haskell.

Pro

Actively-developed functional programming language at the forefront of research

Functional programming is based on the lambda calculus. OCaml is in its functional parts almost pure lambda calculus, in a very practical manner: useful for many daily programming tasks. The acitve development makes improvements to the type system like generalized algebraic data types (GADT) or polymorphic variants, so when learning this language you get at once a down to earth usable compiler and advanced abstraction features.

Pro

Sophisticated and easy-to-use package manager

OPAM is a package manager for OCaml, which is really easy to use, just like npm. It creates a .opam folder in home directory.

The documentation is great as well, and you can switch between multiple versions of OCaml for each project. You can also package your project and publish it on OPAM repositories, even if the dependencies do not exists on OPAM.

Pro

One of the best for writing compilers

OCaml is compiled to native binary, so it's amazingly fast. Being a member of ML-family languages, it has expressive syntax for trees, and has great LLVM support.

Pro

Strong editor integration

The merlin editor tool provides all you need to develop OCaml in your favourite editor.

Pro

Live interactive programming with figwheel

Figwheel builds your ClojureScript code and hot loads it into the browser as you are coding! Every time you save your ClojureScript source file, the changes are sent to the browser so that you can see the effects of modifying your code in real time.

Pro

Easy to use existing JavaScript libraries

Clojure and ClojureScript are designed to be able to interact with their host. So the language by design makes it is easy to use existing JS libraries.

Pro

Targets Google Closure-ready JavaScript for immense optimizations

Google's Closure Library converts regular JavaScript into a highly optimized form - including dead code analysis/elimination. It can even remove pieces of unused code from 3rd party libraries (eg, if you import jQuery but only use one function, Google Closure includes only that piece).

Pro

Simple syntax

Pro

Share application logic between browser and Clojure server

Clojure is also able to run web servers, so one can reap similar benefits to NodeJS in terms of sharing code between client and server.

Pro

Can be used with React out of the box

Pro

Excellent tools for web development

ClojureScript has superb wrappers around React.js (see Reagent) that make building single-page apps a breeze. With figwheel, it's a web dev experience unlike any other -- hotloaded code, repl interaction, and instantly reflected changes make good development fun and fast. You can add things like Garden to make CSS-writing part of the same holistic experience and suddenly all development is a pleasant, smooth process.

Pro

Excellent build tools

Both Leiningen and Boot are great build tools that manage code dependencies and deployment.

Pro

The Spec core library

From the creator of Clojure:Spec is a new core library (Clojure 1.9 and Clojurescript) to support data and function specifications in Clojure.Writing a spec should enable automatic: Validation, Error reporting, Destructuring, Instrumentation, Test-data generation and Generative test generation.

Cons

Con

Strong focus on *nix systems, lacking native support for MS Windows

Lacks native support for Windows systems.

Con

Syntax may seem cryptic to people not used to Lisp

Lisp is sometimes called "syntax-less" and this is bewildering to those steeped in Algol-type syntax (Java, Javascript, C, etc). Being a dialect of Lisp, ClojureScript's syntax may seem cryptic and hard to understand for people not used to it. While Lisp has very little syntax compared to other languages and it's generally considered pretty terse, there's still an initial overhead in learning the language.